Recent cellular systems such as the 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) system, the next generation Personal Handyphone System (PHS), and WiMAX® reuse a single frequency band in adjacent cells to increase the efficiency of frequency use. In using a single frequency band across cells, a terminal at a cell edge may experience interference. Such interference can be reduced by using a signal processing technology involving multiple antennas such as the Adaptive Antenna System (ASS) or Adaptive Array Antenna (AAA). In a time-division duplex (TDD) system, the same frequency is used for both the uplink and the downlink where data from a terminal to a base station is allocated in the uplink and data from a base station to a terminal is allocated in the downlink. Therefore, the reciprocity of channel holds between the uplink and the downlink. Interference can be reduced by applying the weighting factor for the uplink to the downlink.